1. Field of the Invention
The present invention relates to a reclining device for vehicle.
2. Description of Related Art
One example of a conventional reclining device is disclosed in Japanese Utility Model application laid-open No. Sho 58-93254, and FIGS. 1 and 2 illustrate this conventional reclining device. As shown, a plate-shaped lower arm 10 is secured to a side face of a seat cushion (not shown). A rear end portion of the lower arm 10 bends upwards, and a shaft 12 is mounted thereon. An upper arm 14 is secured to a side face of a seat back frame (not shown). A lower end of the upper arm 14 is tiltably fitted on the shaft 12.
A flat ratchet plate 16 having a sector-like configuration is turnably fitted on the shaft 12 in contact with an inside face of a lower end of the upper arm 14, and is caulked on the upper arm 14 with a rivet 18. The ratchet plate 16 has a toothed edge 16a along a lower periphery thereof.
A long plate-shaped pawl 20 is turnably mounted on the lower arm 10 with a pin 22. The pawl 20 has a toothed edge 20a along an upper face of its free end. The toothed edge 20a engages the toothed edge 16a of the ratchet plate 16 to block the turn of the ratchet plate 16 and the upper frame 14 (namely, tilting of the seat back frame). A set plate 24 having a generally T-shaped configuration is secured to the lower arm 10 to hold the ratchet plate 16 and the pawl 20 with the lower arm 10. A lower edge of the lower arm 10 is secured to an upper rail (not shown) of a seat track (not shown) adapted to guide a vehicle seat frontwards and rearwards.
A release lever 26 extends along the lower arm 10. A base end of the release lever 26 is turnably fitted on the shaft 12. The lower arm 10 has a slot 28 of a generally V-shaped configuration. A guide pin 30 fitted in the release lever 26 is inserted into the slot 28, and is secured to an arm plate 32 disposed on the rear side of the lower arm 10. When the seat back is in the fixed state shown in FIGS. 1 and 2, a roller 34 provided around the guide pin 30 abuts a lower face of the free end of the pawl 20 to ensure the engagement of the toothed edges 16a and 20a. The release lever 26 has a slot 36 adjacent to the guide pin 30, and a pin 38 mounted on the pawl 20 is inserted into the slot 36.
The release lever 26 is urged counterclockwise by a coil spring 40 provided between the release lever 26 and the lower arm 10, and the upper arm 14 is urged counterclockwise by a spiral spring 42 provided between the upper arm 14 and the shaft 12.
When the seat back is reclined, a handle 44 of the release lever 26 is lifted to move the guide pin 30 along the slot 28 and separate the roller 34 from the pawl 20. By lifting the handle 44 further, the pin 38 of the pawl 20 moves to the position where the slot 36 alignes with the slot 28, and the pawl 20 separates from the ratchet plate 16. This results in the toothed edges 16a and 20a disengaging, and the upper arm 14 becoming tiltable about the shaft 12.
With the above-described conventional reclining device, the ratchet plate 16 and the pawl 20 are positioned between the lower arm 10 and the set plate 24, as shown in FIG. 2. However, the set plate 24 has an outwardly protruding configuration so as not to contact a head of the rivet 18 adapted to secure the upper arm 14 and the ratchet plate 16 to the arm plate 32. Accordingly, the set plate 24 is spaced from the ratchet plate 16 in the vicinity of the rivet 18. Furthermore, due to the scattering in the assemble positions of the pawl 22, upper arm 14, lower arm 10, set plate 24 or the like, the ratchet plate 16 is apt to displace relative to the pawl 20. As a result, engagement of the toothed edges 16a and 20a is likely to become unstable. In order to solve this defect, conventionally, the ratchet plate 16 has been made thicker than that of the other parts. This arrangement, however, has a problem of the set plate 24 further protruding outwards to increase the thickness and size of the overall reclining device.